Deserialization of Untrusted Data in Pippo

An issue was discovered in Pippo 1.11.0. The function SerializationSessionDataTranscoder.decode() calls ObjectInputStream.readObject() to deserialize a SessionData object without checking the object types. An attacker can create a malicious object, base64 encode it, and place it in the PIPPO_SESSION field of a cookie. Sending this cookie may lead to remote code execution.